New YorK AGRICULTURAL EXPERIMENT STATION. 129 
The above arrangement is one which will appeal to the 
students of this field because it clearly summarizes the ob- 
served results and provides a type for all of the cultures 
which will be found except those which belong to the missing 
eroups above referred to.. Unfortunately this clearness of 
classification is more apparent than real, since practically 
each successive determination of the collection of cultures 
led to a rearrangement of the representatives of the various 
groups with a gradual shifting toward the upper groups be- 
cause of the greater importance placed on a positive result 
than on a negative one. The final accumulation of 33 cultures 
in the upper group is largely the expression of the continued 
action of the law of chance and had the study continued longer 
this group would undoubtedly have been correspondingly en- 
larged. 
An inspection of Table III shows that while some of the 
organisms gave constant results at the various determinations 
a considerable number vibrated from one end of the above 
set of group numbers to the other at different determinations, 
often being classed temporarily with a number of the inter- 
mediate groups. Under such circumstances the above classi- 
fication is seen to represent divisions which are too shifting 
and transient to be designated as species. 
While the authors do not desire to be dogmatic in this con- 
nection the conception has been forced upon them during this 
study extending over a series of years that they were dealing 
with a group of organisms which were very closely related 
and which combined a remarkable stability and uniformity 
with regard to practically all of their culture characteristics 
with a remarkable variability with regard to the results from 
the fermentation tube test with certain sugars. It would 
seem that the correct explanation of this apparent variability 
was the fact that the entire group had a very weak fermenta- 
tive ability and the gas formed from the sugars in question 
was approximately equal to the amount required to saturate 
the fluid in the fermentation tube and provide for the diffu- 
sion which is unavoidable in that test. With the changes 
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